Reinforced metal container and method for making same

ABSTRACT

An improved pail is provided which comprises a curl having a reinforcement member preferably made of plastic mounted therein. The invention further provides a curl press machine which comprises an upper curl die and a lower curl die comprised of radially translating segments. Each lower curl die segment has a tabular end received in a curved slot of a rotating actuator ring. As the actuator ring rotates, the lower curl die segments radially translate. The lower curl die segments further function to support the reinforcement member which reinforces the curl of the pail.

FIELD OF THE INVENTION

[0001] This invention relates in general to product packaging and morespecifically to a reinforced metal container and method for making same.

BACKGROUND OF THE INVENTION

[0002] When chemicals are transported they need to be placed in acontainer that will ensure that the chemicals will not leak into thesurrounding environment in order to avoid health, safety, andenvironmental problems. Therefore, before dangerous chemicals areshipped, the container in which the dangerous chemicals are placed mustbe able to pass the required safety tests to ensure that the dangerouschemicals will not leak from the container, even when the container hasbeen damaged. One of the standardized tests that is imposed by theFederal Department of Transportation on containers used in shippingdangerous or hazardous chemicals is referred to as the ‘drop test.’ Inorder to pass the drop test, the container must not leak after it isdropped from a height proportional to the chemical's specific gravityonto a non-yielding surface. In particular, for steel pails, the droptest must be passed for two different orientations of the container.

[0003] In the first orientation, the center of gravity is aligned withthe point of impact and the bottom chime of the steel pail.

[0004] In the second orientation, the center of gravity is aligned withthe point of impact and the top chime of the container. The droppedsamples are then observed for any leakage of the dangerous chemicals.

[0005] Pails dropped in the second orientation typically fail when thelid crunches or deforms the curl causing the curl to collapse and losestrength. It is known in the prior art that reinforcement of the curlsof large containers with steel wire was effective. Curls of steel pailsare not reinforced with steel wire today because they are manufacturedby automated machinery and reinforcement with steel wire requires manuallabor. Thus it is too expensive to reinforce the curl because of thematerial costs and the manual labor costs. Thus, a pail assembly havinga reinforced curl which overcome the above described disadvantages isdesired.

DETAILED DESCRIPTION OF THE FIGURES

[0006] In the accompanying figures:

[0007]FIG. 1 is a front view of a curl press machine of the presentinvention;

[0008]FIG. 2 is a section view in the direction 2-2 of FIG. 1;

[0009]FIG. 3 is a section view in the direction 3-3 of FIG. 2 whereinthe iris is shown in the open or unengaged position;

[0010]FIG. 4 is a section view in the direction 3-3 of FIG. 2 whereinthe iris is shown in the closed or engaged position;

[0011]FIG. 5 is a section view in the direction 3-3 of FIG. 2 whereinthe iris is shown in the closed position and the pail is undergoing thepress operation in order to form the curl;

[0012]FIG. 6 is a section view in the direction 6-6 of FIG. 3 whereinthe actuator and the iris are in the open position;

[0013]FIG. 7 is a section view in the direction 7-7 of FIG. 4 whereinthe actuator and the iris are in the closed position; and

[0014]FIG. 8 is an enlarged section view of the denoted area in FIG. 3;

[0015]FIG. 9 is an enlarged section view of the denoted area in FIG. 4;

[0016]FIG. 10 is an enlarged section view of the denoted area in FIG. 5;

[0017]FIG. 11A is a perspective view of a steel pail and lid assembly ofthe present invention; and

[0018]FIG. 11B is an enlarged cut away view of a reinforced curl and lidas shown in FIG. 11A.

DETAILED DESCRIPTION OF THE INVENTION

[0019] As shown in the attached FIGS. 1-10, a curl press machine of thepresent invention is shown generally at 10. The curl press machine formsa reinforced curl on a prefabricated metal pail in an automated process.The curl press machine 10 includes a conveyor belt 20 for transporting aplurality of steel pail shells 22 to the press 30. The steel pail shells22 are loaded onto the press 30 so that the upper rim 23 of the pail isaligned for engagement with upper and lower curl dies 40, 42. The curlis formed by pressing the upper rim 23 of the pail in a longitudinaldirection into the upper and lower curl dies 40,42. The upper curl die40 is generally an annular ring and has a cross-sectional shape as shownin FIG. 8. The upper curl die 40 is mounted to the upper portion of thepress 32. The upper curl die 40 has a leading edge 44 for guiding therim 23 of the pail shell 22 into a circular portion 46 of the upper curldie 40.

[0020] The lower curl die 42 is comprised of a plurality of annularsegments 42 which radially traverse inward into a closed or engagedposition as shown in FIGS. 7 and 9 from an outward open position asshown in FIGS. 6 and 8. Each annular segment 42 has an extension 50which is received within a radial groove 52 of the upper die 40. Each ofthe radial grooves 52 guide the radial translation of the annularsegments. Each annular segment further comprises a tabular end 54 whichis received in a curved slot 56 of an actuator ring 60. The actuatorring 60 is slidably received within a flange 34 of the press assembly10. The actuator ring 60 has an extension 62 which is connected to atelescoping actuator 70. As shown in FIGS. 4, 6 and 7, when theactuator's linkage 72 telescopes, the ring 60 rotates about thelongitudinal axis of the press. As the ring 60 rotates, the tabular ends54 of the lower curl die 42 slide in the curved slots 56, causing theannular segments of the lower curl die 42 to move radially inward. Thelower curl die extensions 50 track within the upper curl die groove 52to prevent the annular segments from rotating. The curvature andorientation of the curved slots 56 of the actuator ring 60 are shapedand oriented as best shown in FIG. 6 to allow the annular segments totranslate radially inward and outward. The curved slots are preferablyoriented tangentially. The curved slots are not limited to thegeometrical shape and orientation as shown in FIG. 6 as other shapes andorientations of the slots would work for the invention.

[0021] As shown in FIG. 8, the lower curl die 42 further comprises acurved portion 48 which functions to shape the curl of the pail and loadthe curl with a reinforcement member 80 during formation of the curl.The curved portion 48 of the lower curl die 42 aligns with the curvedportion 46 of the upper curl die 40 when the annular segments are in theradially inward or engaged position as shown in FIG. 9. As the rim 23 ofthe pail 22 is pressed into the upper curl die 40, the rim 23 curlsalong the circular portion 46 of the upper curl die 40 and then downinto the aligned curved section 48 around the reinforcement member 80 asshown in FIG. 10.

[0022] The reinforcement member 80 may comprise metal wire, plastic cordor other suitable material. Preferably, the reinforcement member has acircular cross section and comprises high density polyethylene. It isbelieved that plastic has an advantage over steel wire in that it willslide in the curl upon impact, thereby transferring the impact energyaround the pail in order to dissipate the energy. Metal wire, whileproviding curl reinforcement, will not dissipate the energy aseffectively as plastic, resulting in concentrated energy dissipation atthe point of impact. It is preferred that the reinforcement member havea diameter of about {fraction (5/32)} inches for a five (5) gallonindustrial pail having an outside curl diameter of about {fraction(5/16)} of an inch.

[0023] As shown in FIG. 7, the lower curl die 42 has an opening 90 forloading the reinforcement member 80 into the curved portion 48 of thelower curl die 42 prior to the pressing operation. A feeder mechanism(not shown) measures the reinforcement member being fed into the lowercurl die and cuts the reinforcement member at the appropriate length sothere is a minimal gap in the ends of the reinforcement member.

[0024] Thus as shown in FIGS. 11A and 11B an improved cylindrical pailis shown having a reinforced curl comprising a reinforcement membercontained therein. The improved pail 106 is preferably made of steel andhas a reinforcement member which may be made of plastic. It is preferredthat the reinforcement member be made of a high density polyethylene.The pail may be used in combination with a lid having a plurality oflugs.

[0025] In another embodiment of the invention, the curl may be loadedwith plastic or other suitable material comprising the following steps.First, the shell or cylinder is loaded into a press to partially formthe curl so that a radial gap or opening remains. It is preferred thatthe curl be about 75% to 85% complete. Next, the shell is removed fromthe press and preferably rotated upside down.

[0026] Molten plastic or other suitable material is injected in theradial gap or opening from a nozzle in order to load the curl. After theplastic hardens or cures, the shell is put back in the press in order tocompletely form the curl.

[0027] While the invention has been shown and described with respect tospecific embodiments thereof, this is for the purpose of illustrationrather than limitation, and other variations and modifications of thespecific embodiments herein shown and described will be apparent tothose skilled in the art within the intended spirit and scope of theinvention as set forth in the appended claims.

I claim:
 1. A metal pail comprising a curl reinforced with plastic. 2.The metal pail of claim 1 wherein the plastic is high densitypolyethylene.
 3. A curl press machine for forming the curl of a pail andloading the curl with a reinforcement member, the machine comprising: anannular upper curl die having a curved section; an annular lower curldie having a curved section and being slidable from a first position toa second position; and said curved section of said lower curl dieadapted for supporting said reinforcement member.
 4. The curl pressmachine of claim 2 wherein said lower curl die radially translates. 5.The curl press machine of claim 2 wherein said lower curl die is formedof a plurality of curved segments.
 6. The curl press machine of claim 5wherein said plurality of annular segments have an extension slidablyreceived within a radial groove of the upper curl die.
 7. The curl pressmachine of claim 5 wherein said plurality of annular segments furthercomprise a tabular end received in a curved slot of an actuation ring.8. The curl press machine of claim 7 wherein the actuator ring isrotatably mounted within the curl press machine.
 9. The curl pressmachine of claim 7 wherein the curved slots are tangentially oriented.10. A method for producing a reinforced curl of a pail comprising thefollowing steps: partially forming a curl on the rim of a pail;injecting molten plastic within a gap formed between the end of the curland the pail; allowing the molten plastic to cure; and closing the gapin the curl.
 11. A method for producing a reinforced curl on a steelpail comprising the following steps: loading a curved section of a lowercurl die with a reinforcement member; pressing a rim of a steel pailshell into a curved section of an upper die and down into an alignedcurved section of a lower die around said reinforcement member.